Textile bleach-finish process



Patented Feb. 23, 1954 TEXTILE BLEACH-FINISH PROCESS George Sigler, Buffalo, N. Y., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 8, 1949, Serial No. 131,921

4 Claims.

This invention relates to treatment of textile yarns and fibers to prepare them for weaving operations. More particularly, it relates to a process for finishing and bleaching such yarns and fibers in a single operation, and to a bleachfinish composition suitable for the purpose.

Prior to the instant invention, it has been customary, following the spinning of artificial yarns and fibers from viscose, to successively wash, desulfur, wash, bleach, wash, apply a lubricating finish, and finally dry the spun material. The present market affords numerous bleaching and finishing agents which may be used in the above sequence of operations. For example, the yarn may be bleached with hydrogen peroxide, chlorine water or sodium hypochlorite and, after an intermediate wash, it may be finished with a vegetable or mineral oil or a sulfonated vegetable oil. The finishing agent is of suitable composition to lubricate and otherwise condition the fibers for weaving operations, and to be easily scoured out prior to dyeing.

It has long been desired to reduce the time and expense of these viscose rayon treatments. Numerous purification operations and extended treatment cycles subject the yarn to excessive handling which causes yarn bruises, especially when continuous filament yarn is purified in cake or skein form. Each purification operation, moreover, necessitates a separate solution with its incident cost of preparation and application to the yarn.

In the conventional purification of rayon yarns and fibers, an intermediate wash is necessary before the lubricant finish is applied so that the finish is not oxidized, and thus rendered inefiective, by the concentrated bleaching agent. Since this is true, the bleaching cycle must be long enough and the bleaching agent itself strong enough so that the yarn may be completely purified and bleached during the allocated bleaching cycle.

It is an object of this invention to provide a method whereby textile yarns and fibers may be bleached and finshed in one operation. It is a further object of this invention to provide a bleach-finish solution that can be carried by the yarn through the drying operation, which solution, furthermore, will not degrade or oxidize the yarn even at elevated drying temperatures. It is a still further object of this invention to provide a bleach-finish solution containing a bleaching agent which will not oxidize or degrade the finish material, even though the yarn so treated is dried at an elevated temperature without an intermediate wash. Other objects of the invention will become apparent from the following description and claims.

The objects of the invention are accomplished by impregnating textile yarn or fiber with an aqueous solution containing a finishing agent and a bleaching agent selected from the group consisting of sodium chlorite, organic peracids and alkali metal salts of organic peracids, and drying the impregnated yarn or fiber. In this way the yarn is bleached and finished with a single treatment, washing the yarn is eliminated, and the treatment time is greatly reduced because bleaching continues during drying.

The bleaching agent does not degrade the yarns or fibers to which it is applied, and does not oxidize or otherwise degrade the finishing agent, even though the treated yarns or fibers are dried at an elevated temperature without an intermediate wash. The bleach-finish solution may be applied to the yarn or fibers in various ways. For example, it is possible to apply the solutions of this invention by means of a shower to yarn skeins or to yarn spun by any one of several continuous processes or the solution may be applied to firmly wound yarn packages by centrifugal methods or by the well-known drip purification method. The length of the bleach-finish treatment cycle depends on the type of treatment chosen and on the type of yarn package to be bleached and finished.

The following examples illustrate preferred embodiments of this invention. It is to be understood that the examples, as well as the details included therein, may be altered without departing from the spirit of this invention. In all cases, parts and percentages referred to in the examples are parts and percentages by weight.

Example 1 Viscose rayon yarn produced by the ordinary bucket process is washed with a solution of sodium bicarbonate and then desulfured in the usual manner on regular drip racks with a solution of sodium sulfide and sodium cyanide. The yarn, still in cake form, is then subjected to a final water wash, after which an aqueous bleach-finish solution of the following ingredients is applied on the drip racks:

Sodium chlorite equivalent to 0.05% available chlorine White mineral oil 0.20% Lactic acid suificient to adjust the pH of the solution to. 4.1 to 4.3

Temperature of solution C.

3 Following application of this solution, the cakes are centrifuged and dried at a temperature of 160 F. without washing.

Example 2 Similar viscose rayon yarn is desulfured and washed in cake form in the usual manner. The yarn cake is then centrifugally treated for 15 minutes in a bucket resolved at 3900 revolutions per minute with an aqueous bleach-finish solution of the following ingredients:

Sodium chlorite equivalent to 0.025% available chlorine Sulfonated castor oil 0.25% Lactic acid sufficient to adjust 4.5

the pH of the solution to. Temperature of solution 57 C.

Following the application of this solution, the cakes are centrifugally wrung at 3900 revolutions per minute for 90 seconds and, without any intermediate wash treatment, the cakes are dried at a temperature of 160 F. If desired the washing and wringing treatments may be carried out in buckets revolved at much lower speeds, for example, at 1800 revolutions per minute, with good results.

Yarn treated in accordance with the above examples is found to possess physical properties comparable to the same yarn bleached in any of the conventional ways and followed by the usual application of a finish solution. Moreover, yarn treated as described in these examples possesses a high degree of whiteness and color uniformity, together with a softness and feel equivalent to yarn bleached and finished in any conventional manner.

Example 3 Desulfured, viscose rayon staple fiber of 1.5 denier per filament is shower treated for 4 minutes with an aqueous solution of the following ingredients:

Sodium chlorite equivalent to 0.0025% available chlorine Sulfonated peanut oil 2 grams Der liter Lactic acid sufiicient to adjust 4.2

the pH of the solution to. Temperature of solution 65 C.

The fibers are then dried without an intermediate wash at a temperature of 160 F. The staple fibers so treated show an improvement in whiteness and color uniformity over similar staple fibers bleached and finished according to customary procedures. Moreover, it is found that, even though the bleaching action continues through the drier at the elevated temperature, fibers treated according to this example have tenacities which are at least equal to those of similar staple fibers treated according to the usual bleaching and finishing operations.

Similar viscose rayon staple fiber treated as described above except that the pH of the solution was raised to 7.5 and the temperature lowered to 55 C. resulted in a slight increase of fiber tenacity as compared to fibers treated as described above.

The texture, feel, and color uniformity of fibers treated as described above are comparable to those properties for fibers treated in the conventional manner.

Example 4 Desulfured, viscose rayon staple fiber of 1.5

denier per filament is treated for 4 minutes with an aqueous solution of the following ingredients:

Sodium chlorite equivalent to 0.0025% available chlorine Sulfonated tallow (tallow is a Zgrams mixture of tripalmitin and per liter tristearin) Lactic acid suificient to adjust 4.2

the pH of the solution to.

Temperature of solution 55 C.

The fibers so treated are dried at 150 F. without an intermediate wash. After drying, the fibers show a whiteness comparable to the whiteness of yarns and fibers bleached in the conventional manner with a hypochlorite solution followed by the usual wash. Furthermore, the fiber tenacities are at least equal to those of fibers bleached in the usual manner although, according to this invention, the treated fibers are not washed prior to the drying operation and bleaching of the fibers continues through the drier.

Whereas the examples specify the use of sodium chlorite as the bleach constituent of the solutions of this invention, it should be understood that other bleaching agents may be used in combination with suitable finishing agents. However, the bleaching agent should have an oxidation potential substantially lower than that of the finishing agent used so that the latter will not suffer degradation or otherwise be rendered ineffective by the bleaching agent. The bleaching agent should also be such that its oxidizing power will not materially degrade the yarn when the treated yarn is transferred to the driers without an intermediate wash. Sodium peracetate fulfills these requirements and is an equivalent of sodium chlorite as a bleaching agent for use in combination with finishing agents for the treatment of cellulosic yarns and fibers. It is also possible to use any other organic peracid or its alkali metal salt as the bleaching constituent of the solutions of this invention, provided that the bleach does not oxidize the finish composition used therewith and does not materially degrade the cellulose under the conditions of use.

Finishing agents which may be used, in addition to those specifically mentioned in the examples, include non-oxidizing oils, such as mineral oils and various types of sulfonated vegetable oils, monopole oil, white oil, etc. The concentrations may Vary from 0.1% to 0.5% more or less, preferably 0.2% to 0.3%. Any finishing composition may be applied to the yarns and fibers which is neither oxidized nor impaired by the presence of the bleaching agents used therewith.

The acidity of the bleach-finish solution varies with the nature of the bleach and the nature of the finishing agent employed. With a sodium chlorite bleach, the solution may vary from a pH of 3 to a pH of 7 or higher, but preferably should be maintained in the pH range of 3.5 to 5.0, while the concentration of the sodium chlorite bleach varies from 0.0025% to 0.20% (25 to 2000 parts per million) in terms of available chlorine. The solutions of this invention may be applied as described at temperatures varying from 35 C. to C. The optimum acidity and the optimum operating temperature for solutions not specifically disclosed herein can easily be determined by one skilled in the art.

Although it is preferred to transfer the bleachfinished yarn immediately to the driers, this sequence of operations is not necessary. For example, the bleaching may continue through a la period, after which the yarn may then be dried. The process may be modified to provide for an additional bleaching cycle. For example, it is possible to bleach With a solution of sodium chlorite or some other bleaching agent, wash, and

then apply a bleach-finish solution. This modification makes possible the use of a rather weak solution of the bleaching agent in the final step and so avoids any appreciable degradation of a more or less easily oxidizable finishing agent and promotes uniformity of the finished product.

While the invention has been described in terms of viscose yarn and fibers, yarns and fibers of any composition which are normally bleached and finished in distinct operations may be treated according to this invention, regardless of how the yarns are produced. The invention applies to finishing and bleaching yarns spun in the bucket or centrifugal process, the bobbin process or any continuous or relaxed spinning process. The bleach-finish solution of this invention may also be applied in a manner similar to the application of the usual purification agents to continuously spun yarn, which is customarily treated on-therun.

The invention provides an economical method for combining two essential and heretofore separate and distinct solutions in the purification and processing of yarns and fibers, especially synthetic yarns and fibers. The application of such a combined solution allows these operations to be performed with a minimum of handling of the yarn and hence undesirable yarn degradation is avoided. The bleaching agents may be applied in low concentrations since, according to the preferred embodiment of this invention, the bleaching action takes place as the yarn is carried through the driers and bleaching agents of the type disclosed do not injure the yarn under such conditions. The practice of this invention makes possible savings in time, operating space, equipment and money in applying a combined bleach-finish solution.

As diiferent embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments disclosed except as defined in the appended claims. 1

What is claimed is:

1. The method for bleaching and finishing wet textile yarns and fibers during the drying operation which comprises drying textile fiber impregnated with an aqueous solution containing a finishing oil and sodium chlorite to produce directly a bleached and finished product.

2. The'method for bleaching and finishing wet textile yarns and fibers during the drying operation which comprises drying textile fiber impregnated with an aqueous, weakly acidic solution containing from 0.1% to 0.5% of a finishing oil and sodium chlorite to produce directly a bleached and finished product.

3. The method for bleaching and finishing wet textile yarns and fibers during the drying operation which comprises drying textile fiber impregnated with an aqueous, weakly acidic solution containing from 0.1% to 0.5% of a sulfonated oil and. sodium chlorite to produce directly a bleached and finished product.

4. The method for bleaching and finishing wet textile yarns and fibers during the drying operation which comprises drying textile fiber impregnated with an aqueous solution containing from 0.1% to 0.5% of a finishing oil, 0.0025% to 0.20% in terms of available chlorine of sodium chlorite, and sufficient lactic acid to adjust the pH of the solution to within the range of from 3 to 7 to produce a bleached and finished product.

GEORGE SIGLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,767,543 McKee June 24, 1930 1,905,346 Dreyfus Apr. 25, 1933 2,038,874 Savell Apr. 28, 1936 2,066,371 Stein Jan. 5, 1937 2,092,203 Brennecke Sept. 7, 1937 2,128,612 Hubert Aug. 30, 1938 2,253,368 Dubeau Aug. 19, 1941 2,265,033 Fryer Dec. 2, 1941 2,418,660 OShaughnessy Apr. 8, 1947 2,420,336 Orchard May 13, 1947 2,479,605 Denyes Aug. 23, 1949 FOREIGN PATENTS Number Country Date 188,721 Australia July 18, 1944 

1. THE METHOD FOR BLEACHING AND FINISHING WET TEXTILE YARNS AND FIBERS DURING THE DRYING OPERATION WHICH COMPRISES DRYING TEXTILE FIBER IMPREGNATED WITH AN AQUEOUS SOLUTION CONTAINING A FINISHING OIL AND SODIUM CHLORITE TO PRODUCE DIRECTLY A BLEACHED AND FINISHED PRODUCT. 